Air pollution is believed to have contributed to nearly six million premature births and nearly three million underweight babies worldwide in 2019 , according to a recent meta-analysis. The majority of affected children are born in developing countries.
Air pollution is a major risk factor for the global burden of disease. However, until now, its impacts on perinatal outcomes have been considered suggestive, but not sufficient to infer a causal relationship. Thus, while several modifiable risk factors such as smoking and nutrition have been identified as risk factors for low birth weight or preterm birth, the effects of air pollution have not previously been included, This is despite the overwhelming evidence demonstrating the adverse effects of exposure to PM 2.5 particles during pregnancy.
As part of this work, researchers from UC San Francisco and the University of Washington took an in-depth look at how air pollution affects these different indicators. keys to pregnancy. The team again focused on PM2.5, as it is the most studied pollutant in terms of impacts on perinatal outcomes in epidemiological analyses. In addition, these particles have already been associated with several chronic diseases.
Published in the journal PLOS One, the findings show that air pollution likely contributed to nearly six million premature births and nearly three million underweight babies just for the year 2019, especially in low- and middle-income countries.
In these countries, up to two-thirds of adverse birth effects were linked to indoor air pollution , mainly due to the combustion of coal, manure and wood (heating or cooking food). The remaining third would be related to ambient outdoor pollution caused by the combustion of fossil fuels (motor vehicles and industry).
For the study authors, the global incidence of premature births and low birth weight could be reduced by almost 78% if air pollution was minimized in Southeast Asia and sub-Saharan Africa.
Scientists have yet to fully understand why air pollution appears to be closely associated with preterm birth. More generally, it is agreed that air pollution can lead to toxic products in the blood and stress the immune system. These aggressions could then in turn weaken the placenta surrounding the fetus. Studies have also indicated that soot particles can enter the fetal part of the placenta.
Whatever the cause, researchers say the link between pollution and premature birth is now clear . “The burden of air pollution is huge, but with enough effort, it could be greatly reduced “, notes Dr. Rakesh Ghosh, lead author of the study. "With this new global and more rigorously generated evidence, air pollution should now be considered a major contributor to childhood morbidity and mortality, not just chronic adult diseases “.
